---------------------------~-- "'~. Developmental Aspects of Immunoglobulins and Antibodies Herwart Ambrosius Institute of Zoology, University, D-Leipzig Summary: Zusammenfassung: Aspekte der Entwicklung von Immunglo- This short review discusses the evolulution of the immu- bulinen und Antikorpern. noglobulins and the development of the diversity of antibod- Die vorliegende Ubersicht diskutiert die Evolution der ies. Birds and mammals represent two lines of development Intmunglobuline und die Ausbildung del' Vielfalt del' having divided more than 300 million years ago. In the Antikorper. Vogel und Siiugetiere sind heutige Typen von immunoglobulins and antibody-systems there are many Entwicklungslinien, die sicti vor mehr als 300 Millionen similarities which, however, are based on analogies. In this Jahren getrennt haben. In den Immunglobulinen und sense the dominant humoral type of immunoglobulin is Ig Y Aruikorpersystemen gibt es viele Ahnlichkeiten, die jedoch in birds as opposed to IgG in the mammals. Also, the oft auf Analogien beruhen. So ist der dominierende humora- mechanisms differ which lead to the diversity of antibodies. le Immunglobulintyp der Vogel das IgY im Gegensat: zum In mammals predominantly recombination of gen-segments IgG der Siiugetiere. Auch die Mechanismen, die zum and somatic mutations lead to this diversity, in birds gen- Antikorperrepertoire fuhren, sind unterschiedlich. Bei den conversion shows a greater significance. In this way Siiugetieren sind es VOl'allem Rekombination der Genseg- comparable results are produced through different struc- mente und somatische Mutationen, die das groj3e Antikor- tures or mechanisms. perrepertoire liefern, wdhrend bei Yogeln der Prozej3 der Genkonversion die grofste Bedeutung hat. So werden im Keywords.immunoglobulins, Ig Y, IgG, evolution, diversity, Immunsystem der Vogel und Siiugetiere vergleichbare birds, mammals Leistungen durch unterschiedliche Strukturen bzw. Mecha- nismen erreicht. 1 Evolution of immunoglobulins mune reaction of the hagfish again, but weight immunoglobulins of non-mam- he adapted the animals to a higher malian vertebrates, they were called IgG In the fifties and the sixties the group water temperature. After antigen injec- in analogy to the dominant humoral of Robert Good in Minneapolis studied tion he found proteins with binding immunoglobulin class of mammals. But the ontogeny and phylogeny of the activity to the antigen and believed to in the paper of Leslie and Clem (1969) immune system. One of the main have induced antibodies (Raison et aI., about the low molecular weight immu- results was the finding that the thymus 1978). But in 1994 he questioned his noglobulin of the chicken, the chicken plays an essential role in the immune previous results after new experiments, immunoglobulin was called IgY and system. The first data about the dichot- assuming the induced proteins to be showed well defined differences be- omy of the immune system with the complement components. tween that immunoglobulin and the IgG humoral and the cell-mediated parts Because published data about the of mammals. Unfortunately, the conclu- were found using the chicken as exper- antibodies of other groups of cyclos- sions of Leslie and Clem were not noted imental animal. It could be shown that tomes, especially the lampreys, are by the majority of later authors. Only the thymus is a primary immune organ. very controversial, hard facts about the during recent years the name IgY has It is the origin of the thymus-dependent humoral immune response begin with been accepted for the dominant humoral lymphocytes and a regulatory organ cartilaginous and bony fishes and in- low molecular weight immunoglobulin also in the humoral immune response. clude all other groups of vertebrates. of amphibians, reptiles, and birds, as in One question, already dealt with by The only immunoglobulin class, oc- the review of WaIT et al. (1995). Robert Good, is about the most primi- curing in all vertebrate groups from Already in 1977 we published data tive species with a functioning immune fish to mammals, is the IgM. In some about the low molecular weight immu- system. Good and his coworkers stud- species, especially in bony fishes, it noglobulins of amphibians, reptiles, ied the hagfish Eptatretus stouti, a can be found in different types, and for and birds in comparison to the immu- cyclostome, and could not find a thy- special functions. noglobulins of mammals (Hadge et al., mus or induce antibodies. So they One question, discussed for many 1977). These investigations about the called the hagfish the "negative hero" years, concemes the first appearance of immunoglobulins of non-mammalian of immunology. A few years later low molecular weight antibody class in vertebrates have been extended in the Robert Raison in the lab of Bill Hilde- phylogeny. Throughout many years, in following years and produced the fol- mann in Los Angeles studied the im- nearly all papers about low molecular lowing picture: 10 ALTEX 13, SUPPLEMENT 96 :!in AMBROSIUS --~~------¥~ ------------------------ 2 Structure of IgY-immuno- Table 1: Relative Molar Mass of the Heavy and Light Chains of Low Molecular globulins Weight Immunoglobulins of Different Vertebrates (Six Estimations) Molar Mass (in KD) There are well defined structural diffe- rences of IgY-type immunoglobulins Species Ig Type H Chains L Chains and the 19G. That includes the molar mass of the heavy chains (table 1) and Man IgG 52 (Ref. Value) the carbohydrate content of the immun- Cow IgG 52.5 23,0 oglobulins (table 2). Guinea-Pig IgG 2 51,7 23.0 On the other hand, the IgY-type Chicken IgY 62.8 22.0 immunoglobulins are much less flexi- Duck IgY 62.7 24.5 ble than IgG as shown by fluorescence Goose IgY 64.3 25.0 polarisation technique (table 3). But Tortoise Agrion. horsf. IgY 65.5 24.0 the comparison of the data of the IgY Lizard Ophis. apodus IgY 64.5 25.5. of frog, tortoise, and chicken show a Frog Rana esculenta IgY 64.0 21.0 significant higher flexibility of the Data from Hadqe et aI., 1980 chicken IgY than the other IgY types. Also, the structures of the Fe part of the immunoglobulin isotypes IgY and Table 2: Carbohydrate Composition of Immunoglobulins of Different Vertebrates IgG are different. The Fe part of IgY is thinner than the Fe part of IgG and Species Ig Type Hexos. Content (in %) Sialic acid does not contain any hole in its middle Hexosamines Total part, as was revealed for the IgG Fe fragment (Cser et al., 1982). The ab- Man IgG 1.3 1.0 0.1 2.4 sence of the hole agrees with the Guinea-Pig IgG 2 1.3 0.9 0.1 2.3 supposition that the excess mass in the Chicken IgY 3.2 1.8 0.2 5.2 6.4 H-chain is distributed in the Fe region Duck IgY 4.5 1.7 0.2 near the centre of mass of the whole mo- Tortoise IgY 3.2 1.1 0.2 4.6 lecule, and it also supports the observa- Data from Hadqe et aI., 1980 tion that chicken IgY is less flexible in comparison with mammalian IgG. Unfortunately, the comparison of Table 3: Rotational Correlation Time of DNS-Conjugates of Immunoglobu- amino acid sequences is hardly suitable lins of Different Vertebrates for the elucidation of the relationships between the different immunoglobulin DNS-Conjugate Oocalc (nsec) OhexP (nsec) Oh/Oo classes occuring in the different verte- brate groups because the differences Frog IgY 54 67 1.24 are too great. It only points to IgY as Tortoise IgY 54 68 1.26 the ancestor of IgG and IgE (Warr et Chicken IgY 61 43 0.69 al., 1995). On the other hand, the Human IgG 59 20 0.35 phenomenon of immunological cross- Data from Zagyansky, 1975 reactivity could be used very success- fully for the identification and classifi- cation of immunoglobulins in species other than man which also corresponds as quantitative value for the antigenic points to a strong relationship to the with the nomeclature rules (WHO re- cross-reactivity which is nearly identi- chicken IgY. On the other hand, the port, 1969; Ambrosius et al., 1978). cal with the structural relationship. IgG-type immunoglobulins do not in- The technique mostly used for the Extensive experiments of Dietlind hibit the antigen-antibody system measurement of antigenic cross-reac- Hadge and others in our laboratory measurably. Therefore, no clear rela- tivity of proteins, is the inhibition of with alltogether 43 different antisera of tionship is detectable. IgG antibodies binding of specific antibodies to the different experimental animal species are only found in mammals. The struc- radio-labelled antigen by the proteins showed that the dominant humoral low tural difference between IgY and IgG to be compared. Fig. 1 shows the molecular weight antibodies of the are not surprising in light of the fact results of such an experiment, using non-mammalian vertebrates, excluding that the evolutionary lines of reptiles carp anti-chicken IgY antibodies of H- fishes, are all of the IgY type. Table 4 and birds separated from the one of the chain specificity and different immu- shows the data of experiments with mammals in the Permian or even earli- noglobulin preparations as inhibitors IgY fragment-specific carp antibodies. er, which means 300 million years ago. (Ambrosius and midge, 1987). Be- The 50 % inhibition values are, in the This is independent of the possibility cause in that system the point of 50 % cases of IgY-type immunoglobulins, that IgY may be the ancestor of IgG inhibition is measurable, it can be used always in the range of 1-2000 which (Warr et al., 1995). ALTEX 13, SUPPLEMENT 96 11 AMBROSIUS ~r;") ---------------------------h~~-- ~0~,,~. IN HI BiTtON ['f,] 31gB in birds In 1972 several authors found a third Ig class in the blood serum and in the secretions of chickens with H chains clearly different in structure and anti- genicity from H chains of IgM and IgY (Bienenstock et aI., 1972; Lebacq- Verheyden et aI., 1972; Orlans and Rose, 1972).